Mounted and free pulleys, ropes routed through tangent points, Atwood machines — the rope follows the pulley automatically.
Pulley diagrams fail two ways: ropes that don't touch the rim, and pulleys
floating without a support. The DSL fixes both — mount=strut
grows a support rod, and rope ... through=p1 computes the tangent
points and wraps the rope over the rim.
pulley p1 mount=strut of=ceiling draws the mounting rod from
the surface down to the hub — the pulley stays attached when things move:
canvas 400x200 surface ceiling x=100 y=40 w=200 h=14 pulley p1 mount=strut of=ceiling anchor=ceiling.bottom angle=90 len=60
One pulley, two masses, one rope. Pin each mass under a side tangent
(9oclock/3oclock), then route the rope
through=p1 — no manual endpoint wiring:
canvas 420x300 surface ceiling x=110 y=40 w=200 h=14 pulley p1 mount=strut of=ceiling anchor=ceiling.bottom angle=90 len=60 block m1 w=50 h=40 label="m1" block m2 w=50 h=40 label="m2" m1.center.x = p1.9oclock.x - 20 m2.center.x = p1.3oclock.x + 20 m1.top.y = p1.center.y + 60 m2.top.y = p1.center.y + 110 rope r1 from=m1.top to=m2.top through=p1
rim:deg and clock:N give exact tangent points —
p1.9oclock is the leftmost rim point.through=..under in the through list wraps the rope beneath a pulley.